As a method for generating a stable voltage lower than an input voltage, a non-insulation type voltage dropping chopper circuit is widely used.
Japanese Unexamined Patent Application Publication (JP-A) No. 2006-311646 discloses a voltage dropping chopper circuit that generates a second DC voltage from a first DC voltage by controlling a switching element connected to an inductor.
In the present specification, a switching element denotes an element capable of performing conduction control between input and output by controlling a voltage applied to a control terminal (a base terminal or a gate terminal) of a bipolar transistor, a MOSFET and the like.
A control IC (Integrated Circuit) controlling the switching element in the voltage dropping chopper circuit includes a first ground terminal and a second ground terminal that is pulled down by an external resistor.
In the voltage dropping chopper circuit, in a normal state, the first ground terminal is connected to a control circuit section of the control IC for controlling the on-and-off timings of the switching element. When the first ground terminal is open, the control IC connects the control circuit section to the second ground terminal, thereby preventing an overcurrent from flowing through the switching element.